59 terms

Chapter 3: Digestion, Absorbtion, and Metabolism

Class
STUDY
PLAY
Atoms
Smallest unit of an element
Element
Cannot be broken down into products with different properties.
GI tract
Mouth, pharynx, esophagus, stomach, small and large intestines,
Transit time
The time between the ingestion and elimination of food waste.
Enzymes
Protein molecules that a accelerate the rate of specific chemical reactions without being changed themselves.
Pepsin (stomach)
Breaks proteins into polypeptides and AA. Secreted in gastric juice in inactive form and activated by acid in stomach.
Trypsin and chymotrypsin (pancreas)
Breaks proteins and polypeptides into shorter polypeptides.
Carboxypeptidase
Breaks polypeptides into AA.
Sucrase
Breaks sucrose into glucose and fructose
Lactase
Breaks lactose into glucose and galactose
Maltase
Breaks maltose into glucose
Antigen
A foreign substance that simulates an immune response:
Antibodies
Proteins produced by cells that destroy or inactivate foreign substances.
Saliva
Secreted by salivary glands.
Salivary amylase
Enzyme that breaks down starch.
Lysozyme
Enzyme in salvia, tears, and sweat that destroys certain types of bacteria.
Epiglottis
Piece of elastic connective tissue at the back of throat that covers the openings of passageway to the lungs during swallowing.
Esophagus
Extends from the pharynx to the stomach.
Peristalsis
Muscular contractions that move food through the GI tract.
Sphincter
Muscular valve that controls the flow of materials in the GI tract
Chyme
Mixture of partially digested food and stomach secretions.
Gastric juice
Composed partly of hydrochloric acid
Parietal cells
Cells in the stomach lining in gastric pits, makes hydrochloric acid and intrinsic factor in response to nervous or hormonal stimulation.
Pepsinogen
An inactive protein-digesting enzyme produced by gastric glands and activated to pepsin by acid in the stomach.
Pepic ulcer
Open sore in lining of stomach, esophagus, or small intestine. Leading cause of ulcer is Helicobacter pylori bacteria.
Gastrin
Hormone secreted by stomach mucosa that stimulates the secretion of gastric juice.
Pyloric phincter
Helps regulate the rate at which food empties the stomach.
Villi (villus)
Finger-like protrusions of he lining of he small intestine that participate in absorption of nutrients. Each contains a lacteal.
Microvilli or brushborder
Increase the absorptive surface area in the small intestine.
Lacteal
A lymph vessel in intestine that absorbs and transports the products of fat digestion.
Segmentation
Rhythmic local constrictions of he intestine that mix food and digestive juices and speeds absorption by moving food mass over intestine wall.
Pancreas
Secretes digestive enzymes and bicarbonate ions into small intestine during digestion. The bicarbonate ions neutralize chyme making the environment in small intestine less acidic then stomach.
Gallbladder
Organ that stores bile, which is produced by liver.
Lipases
Fat-digesting enzymes
Bile
Made by liver and stored by gallbladder. Emulsifies fat allowing lipases to be more effective on fat.
Secretin
Hormone released by the duodenum that signals the release of pancreatic juice rich in bicarbonate ions and stimulates the liver to secrete bile into gallbladder
Cholecystokinin (CCK)
Hormone released by the duodenum that stimulates the release of pancreatic juice rich in digestive enzymes and causes the gallbladder to contract and release bile into duodenum.
Colon
Largest portion of large intestine.
Rectum
Connects colon to anus.
Intestinal microflora
Microorganisms that inhabit the large intestine.
Gastroesophageal reflux disease (GERD)
Chronic condition in which acidic acid stomach contents leak back up into the esophagus damaging it and causing pain.
Enteral
Method of liquid feeding by placing tube down I stomach or intestines.
Total parenteral nutrition (TPN)
Providing nutrients directly into circulatory system.
Atrophic gastritis
Inflammation on stomach lining that may decrease absorption of vitamins and minerals and may allow bacterial growth.
Hepatic portal circulation
System of blood vessels that collect nutrient-laden from digestive organs and delivers it to liver.
Lymphatic system
System that drains excess fluids from spaces between cells, transports fat-soluble substances from digestive tract.
Capillaries
Where exchange of gases and nutrients between blood and cells occur.
Veins
Carry blood towards the heart.
Arteries
Carry blood away from the heart.
Metabolic pathway
Series of chemical reactions inside of an organism that results in the transformation of one molecule into another.
Coenzyme
A molecule (not protein but sometimes a vitamin) that is necessary for the proper functioning of many enzymes.
Cellular respiration
The reactions that break down glucose, fatty acids, and amino acids in the presence of oxygen to produce carbon dioxide,water, and energy in the form of ATP.
Aceyl CoA
Metabolic intermediate formed during the breakdown of glucose, fatty acids, and AA. It is a 2-carbon compound attached to a molecule of CoA.
Citric acid cycle (krebs cycle or tricarboxylic acid cycle)
Stage in cellular respiration where 2 carbons from acetyl-CoA are oxidized. Producing 2 molecules of carbon dioxide.
Oxidized
Lost an electron
Reduced
Substance gained an electron.
Glycogen
Storage form of carbohydrate.
Nephron
Functional unit of kidney. Performs the job of filtering blood and maintaining fluid balance.
Glomerulus
Ball of capillaries in nephron that filters blood during urine formation.